A method used for creating a three dimensional (3D), or stereoscopic, image has been used for some time now, primarily in movie theaters. It generally involves creating two images for each frame, one indented for the left eye and one intended for the right. In movie theaters, these images are displayed simultaneously. The viewer wears specialized glasses that filter the appropriate images for each eye. More specifically, the left lens of the glasses filters out the right image so the left eye only sees the left image. Similarly, the right lens of the glasses filters out the left image so the right eye only sees the right image. When the images are combined in the brain the illusion of depth is created and the viewer sees a “3D” image.
Modern televisions with 3D capability use a more complicated active shutter method. Just as with movie theaters, two images are created for each frame, one for the left eye and one for the right eye. The viewer also must wear specialized glasses. However, instead of using filters to distribute the images to the appropriate eye, each lens closes, or shutters. The television also does not display the images simultaneously. In operation, the television displays the left image and the right lens shutters allowing only the left eye to see the left image. Then, the television displays the right image and the left lens shutters allowing only the right eye to see the right image. This process repeats very rapidly and the viewer does not notice the shuttering. This is how the illusion of depth is created. While the active shutter system is the most widely used 3D technology for the television, passive/polarized lens systems are additionally on the market. Further, there are systems that do not need glasses, although they have significant draw backs when in the 3D mode.
The active shutter method creates a synchronizing issue, when there is a 3D format change. For instance, when converting from a side-by-side 3D format to a top-to-bottom 3D format, the placement of the two perspective changes. The television may be instructed of the switch, but it is not provided with any information about exactly when the change will occur. Accordingly, the source of the 3D content changes format and the television changes how it reads the content, but there is no synchronization for the change. In other words, the television may change format at a different time from the format change of the 3D content from the source, resulting in a poor image.
The operation of a conventional television viewing system will now be described with reference to FIG. 1.
FIG. 1 illustrates a conventional television viewing system 100 operable to display content from a television service provider (not shown).
Conventional television viewing system 100 includes a set-top box 102, a video unit 104 and a remote control unit 106.
Set-top box 102 is arranged to receive an input signal 108 from a television service provider (not shown), to receive a remote control signal 112 and to output an output signal 110. Video unit 104 is arranged to receive output signal 110. Remote control unit 106 is arranged to output remote control signal 112.
Communication between any of the elements of conventional television viewing system 100 may be accomplished by way of any known communication media. Signals typically embody computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism and include any information-delivery media. Non-limiting examples of communications media between any of the elements of conventional television viewing system 100 include wired media, such as wired networks and direct-wired connections, and wireless media such as acoustic, radio-frequency, infrared, etc. The term “tangible computer-readable media” as used herein includes both storage and communications media.
Further, in some embodiments at least one of the elements of conventional television viewing system 100 may be implemented as tangible computer-readable media for carrying or having computer-executable instructions or data structures stored thereon. Such tangible computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer. Non-limiting examples of tangible computer-readable media include physical storage and/or memory media such as RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. When information is transferred or provided over a network or another communications connection (hardwired and/or wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a tangible computer-readable medium. Thus, any such connection is properly termed a tangible computer-readable medium. Combinations of the above should also be included within the scope of tangible computer-readable media.
Remote control unit 106 is operable to send commands from the user to set-top box 102. Non-limiting examples of commands include those for changing the channel, displaying content information and displaying the channel guide. Set-top box 102 is operable to process television content from input signal 108 into an appropriate signal for video unit 104. Video unit 104 is operable to display video and to play audio content processed by set-top box 102. Non-limiting examples of video unit 104 include a television, hand-held communication device and a computer.
In operation, the user would utilize remote control unit 106 to send commands to set-top box 102. For the purposes of explanation, assume that a command or series of commands are used to select a channel. Remote control unit 106 would send the command or commands through remote control signal 112. Remote control unit 106 may be any known remote control unit, non-limiting examples of which include a computer, a cellular phone, and a dedicated remote.
Once set-top box 102 has received remote control signal 112, set-top box 102 will then process input signal 108 and create output signal 110. Video unit 104 then presents the audio and video included in output signal 110 to the user.
A more detailed description of the operation of set-top box 102 will now be described with reference to FIG. 2.
FIG. 2 illustrates an example block diagram of set-top box 102 of FIG. 1.
As illustrated in FIG. 2, set-top box 102 includes a receiver portion 202, a decoder 204, a compositor 206, a graphics device 208 and an output portion 210.
Receiver portion 202 is arranged to receive input signal 108 and to output input data 212. Decoder 204 is arranged to receive input data 212 and to output decoded data 214. Graphics device 208 is arranged to output display graphics 216. Compositor 206 is arranged to receive decoded data 214, to receive display graphics 216 and to output composite data 218. Output portion 210 is arranged to receive composite data 218 and to output output signal 110.
Receiver portion 202 is operable to perform many functions. At a minimum, receiver portion 202 performs the function of a tuner. A tuner retrieves the appropriate channel data from input signal 108. In another example, receiver portion 202 may also perform the function of a decrypter. A decrypter is needed if input signal 108 is encrypted. Decoder 204 is operable to decompress compressed data. A non-limiting example of a compressed data type is MPEG4.
Graphics device 208 is operable to generate the display graphics and may include multiple portions. These portions may include memory where graphics are stored and a graphics processor. Non-limiting examples of display graphics include a channel guide and content information.
Compositor 206 combines the video with display graphics. A non-limiting scenario of combining video with display graphics includes when the channel guide is called by the user. In this example, compositor 206 may shrink the channel video and place the channel video in the upper right corner of the channel guide.
Output portion 210 is operable to interface the content to be displayed with video unit 104. A non-limiting example of a television interface is HDMI.
In operation, input signal 108 is received by receiver portion 202. Input signal 108 includes data for a multitude of channels provided by the television service provider. Data for each channel includes audio data, video data and meta-data.
Meta-data is used by devices to determine the format of the channel video data. There are a multitude of possible formats for channel video. For 2D video, the format can be one of many resolutions. For 3D video, the 2D format parameters are augmented by parameters to describe how to derive both (or more) perspectives. One example 3D format is the left eye image on the left, the right eye image on the right and both images at the same resolution.
Returning to FIG. 2, receiver portion 202 may perform multiple functions, a non-limiting example of which includes tuning. In this example, assume receiver portion 202 only acts as a tuner. In this case, receiver portion 202 filters out all data except for the data for the channel selected by the user. This is input data 212 and includes, but is not limited to, audio data, video data, and meta-data. Input data 212 is then transmitted to decoder 204.
Decoder 204 then decompresses input data 212. It is common for television service providers to compress the data sent to the users. This data must be decompressed before further processing can begin. An example compressed data file format is MPEG4. Decompressed data 214 is then sent to compositor 206. Compositor 206 also receives information from graphics device 208.
When necessary, graphics device 208 creates the graphics that will be displayed on the television. The graphics than can be displayed include at least one of the group including the channel guide, video information and subtitles. The graphics that will be displayed can be chosen, for example, by the user using remote control unit 106, or software (not shown) in set-top box 102. Once the appropriate graphics have been generated, display graphics 216 is set to compositor 206.
Compositor 206 will combine decoded data 214 and display graphics 216 into one signal. Compositor 206 also determines how the channel video and graphics will be displayed on the screen. For example, when the user sends a command to display information on the program being displayed, compositor 206 will overlay display graphics 216 on decoded data 214, creating composite data 218, which is then sent to output portion 210.
In the event graphics are not to be displayed, compositor 206 does not combine graphics with decoded date 214. In this case, composite data 218 only includes decoded data 214.
Output portion 210 converts composite data 218 into a data format compatible with video unit 104, creating output signal 110. A common format type for high definition televisions is HDMI. Output signal 110 includes the same audio data and video data received by receiver portion 202. An HDMI interface (not shown) returns the television's capabilities, which can be used for selecting the preferred video format.
Referring to FIG. 1, video unit 104 will now display the video and play the audio from the channel selected by the user. For the purposes of explanation, assume the video format of the current channel does not match the video format of the previous channel. In this case, video unit 104 would need to change video formats to match the video format of the video data. This would cause video unit 104 to re-synchronize with the video data, resulting in an ugly transition in the video.
If the transition is from a channel displaying 3D content to a channel displaying 2D content, the user can watch the 2D content while wearing 3D glasses. The glasses are awkward to wear, so people generally take their glasses off when they are not needed. If the transition is from a channel displaying 2D content to a channel displaying 3D content, the user will need to find and wear the 3D viewing glasses. If the transition is from a channel displaying 3D content in one video format to a channel displaying 3D content in another video format, there will be an ugly transition between the channel videos. What is needed is a method of switching between channels of different video formats without causing an action by the user or interrupted video clarity.
In view of the foregoing, there is a need for improved techniques for providing switching between channels of different video formats without causing an action by the user or interrupted video clarity.